Certain air traffic control schemes rely on path conformance. For example, an air traffic controller may assign a flight path to an aircraft. The flight path may be selected to avoid potential conflicts (e.g., with other aircraft). The aircraft may be expected to stay on the flight path to within particular navigation parameters. For example, the aircraft may be expected to maintain the flight path within Required Navigation Performance (RNP) values. The RNP value defines a volume of airspace or “tunnel” around the flight path that may be referred to as the RNP path. The aircraft is expected to stay contained within the boundaries of the RNP path.
The air traffic controller may be responsible to monitor the aircraft to ensure that the aircraft conforms to the RNP path. For example, the air traffic controller may be provided with a high-refresh-rate radar display. The radar display may show a most recent position of the aircraft based on radar return information. Additionally, the radar display may show a previous position of the aircraft. Thus, the radar display may indicate whether the aircraft is currently conforming to the RNP path. To estimate whether the aircraft is expected to conform to the RNP path at a future time, the air traffic controller may mentally extrapolate a subsequent position of the aircraft based on the previous position and the most recent position. Alternately, the controller's automation may provide this extrapolated position for them.